As the popularity of the Internet has increased, so has the prevalence of social networking websites and applications. Generally speaking, a social network refers to an application or service that facilitates the building online communities of people who share interests and activities, or who are interested in exploring the interests and activities of others. Many social network services are web-based and provide a variety of ways for users to interact, such as e-mail and instant messaging services. Some examples of social networking websites are delicious (http://delicious.com), facebook (http://www.facebook.com), Yahoo! Movies (http://movies.yahoo.com), Yahoo! Music (http://music.yahoo.com), Flickr (http://www.flickr.com), and others.
Advertisers often leverage social networks to market an increase awareness of their products and services. For example, advertisers often use “viral marketing” which generally refers to marketing techniques that use pre-existing social networks to produce increases in brand awareness or to achieve other marketing objectives (such as product sales) either through word-of-mouth or through self-replicating viral processes, analogous to the spread of pathological and computer viruses. Viral marketing promotions may take many forms, including video clips, interactive Flash games, advergames, ebooks, brandable software, images, or even text messages.
In addition, advertisers often deliver advertising using contextual advertising. Contextual advertising is marketing targeted to the specific individual visiting a website or a page within the website. A contextual advertising system may scan the text of a website for keywords, scan metadata related to the individual (e.g., geographical or other demographic data based on cookies or other metadata associated with the user) and return “personalized” advertisements to the webpage based on such keywords and/or metadata. For example, if the individual is viewing a website pertaining to sports and that website uses contextual advertising, the individual may see advertisements for sports-related companies, such as memorabilia dealers or ticket sellers. In addition, the advertisements may be for such companies physically located in the same geographical region as the individual. Contextual advertising may also be used by search engines to display advertisements on their search results pages based on the keywords in a user's search query.